I have a crack in my foundation that previous owners had filled with epoxy. The crack has opened up slightly at some point in the last 8 years. Is there anything I can do to determine (short of calling in a foundation company) if there are serious things going on with the foundation here? What can I do to assess what is going on?
There are several issues: 1) location of crack, 2) horizontal crack and small vertical crack, 3) seismic zone where you live, 4) form ties
1) The crack appears in the top portion of your foundation. This means it’s probably from freeze-thaw issues. (If the crack was in the lower half of the wall, it could indicate a weak foundation wall that could be leaning and getting pushed in.)
Do you get water seeping in the crack? If so, it would be an indication that water is penetrating the wall and then freezing, which causes expansion and then cracks.
If so, you’ll need to dig up the area outside the cracks, apply a foundation sealer and then install a drainline to carry water away from the foundation.
2) A horizontal crack indicates freeze / thaw issues rather than settlement issues. That’s good for you.
3) You live in a high seismic zone. Concrete walls require additional reinforcement in your zone. I suspect that reinforcement has been installed, because there are no other horizontal cracks in the wall.
4) It seems unusual that the horizontal cracks go directly across where the form ties are located. Perhaps when the forms were removed a slight crack developed which now allows water to penetrate the wall and then freeze.
In summary: If it’s leaking, I’d do the outside repair (sealer and drainline) and if it’s not, you could monitor it and see if it gets worse. (Btw, I’d make sure downspouts are connected and drain away from the wall and make sure the ground slopes away from the house.)